1. Field of the Invention
This invention relates to apparatus for producing one-sided corrugated paperboard using two corrugated rollers.
2. Description of the Prior Art
Prior Art French patent FR-PS 1 467 195 discloses high pressure chambers on both sides of a glue applying roller, by means of which a corrugated paper sheet is pressed, area by area, against a corresponding corrugated roller. The high pressure chambers are directly sealed off against the corresponding corrugated roller. As a result, the application of glue dispensed onto the paper sheet is impaired.
German patent DE-OS 34 37 190 discloses a device for sealing off the edges of pressure chambers formed on both sides of a glue applying roller against a corrugated roller or a pressing roller. The other edges of the pressure chambers are sealed off against the glue applying roller. The glue applying roller is provided with longitudinal grooves, the circumferential distribution of which corresponds to the distribution of teeth disposed on the corresponding corrugated roller. The glue to be applied is drawn from the troughs of the grooves on the glue applying roller. The sealing portions of the pressure chambers rub against the tops of the grooves and remove the glue therefrom. The excess glue which has been applied is not significantly diminished by the sealing portions of the pressure chambers, but the construction of the longitudinal grooves on the glue applying roller and the synchronous motion of the glue applying roller with its corresponding corrugated roller is expensive. In addition, at high operating speeds, glue particles are spun off during the transfer of the glue onto the corrugated roller. The application of the glue is thereby disrupted.
German patent 29 35 677 discloses apparatus to enclose the glue mechanism with a single pressure chamber which is connected to a pressure source. The edges of the pressure chamber are sealed off by sealing elements engaged against a pressing roller or the paper sheet with its associated corrugated roller. The corrugated roller entraining the corrugated sheet is provided with several annular grooves positioned at a distance from each other. By means of the annular grooves, the internal side of the corrugated sheet is brought into contact with the pressure source. The areas of the corrugated sheet between the glue applying roller and the corrugated roller or pressing roller are stressed with uniform pressure. This is disadvantageous for the application of glue. The danger is present, during transfer of the glue at high operating speeds, that a larger number of drops of glue will be spun off. In addition, the glue mechanism can only be maintained, during the use of a single pressure chamber, through access apertures within the chamber. Maintenance of such structure is complicated.